1. Field of the Invention
This invention relates generally to an apparatus for imparting mechanical torque to effect a braking action. The invention relates more specifically to an apparatus which effects the braking action by transferring the energy of a rotating sprocket into spring oscillation, and then from spring oscillation into heat by means of damping.
2. Description of Related Art
Various conventional devices are known for imparting mechanical torque to effect a braking action. Such devices include, for example, Prony brakes and disc brakes.
Many of the aforementioned conventional devices, however, suffer from various drawbacks, including bulkiness, excessive weight, a general lack of mechanical reliability, and insufficient flexibility for use in wide variety of applications. Most importantly, however, these devices are characterized by a direct reliability upon friction to effect the braking torque.
Therefore, a general need exists for an apparatus capable of imparting mechanical torque to effect a braking action, wherein the apparatus is compact, lightweight, mechanically reliable, and has sufficient flexibility for use in a variety of applications. A more specific need exists for an apparatus capable of imparting constant mechanical torque to effect a braking action, wherein the operation of the apparatus should be essentially independent of friction and temperature, as well as independent of rotational speed.
It is an object of the present invention to provide an apparatus for imparting constant mechanical torque to effect a braking action. It is a further object of the present invention to provide an apparatus to effect the braking action which is compact, lightweight, and mechanically reliable, has sufficient flexibility for use in a variety of applications, and is capable of effecting the braking in a constant, smooth, and adjustable manner. It is a still further object of the present invention to provide the aforementioned apparatus wherein the operation of the apparatus is essentially independent of friction and temperature, as well as independent of rotational speed.
Accordingly, the present invention advantageously employs an apparatus which effects the braking action by transferring the energy of a rotating sprocket into spring oscillation, and then from spring oscillation into heat by means of damping.
The braking apparatus comprises a hub assembly having a hub, a collar, a plurality of torsional springs, a spring cap, a spring bushing, and damping means, and a sprocket assembly having a sprocket, a hub bearing, a retaining ring, and a plurality of roller assemblies each of which has a roller. The sprocket assembly is rotatably connected to the hub assembly by a hub assembly spring, a sprocket assembly spring, an adjustment cap, and an adjustment means.
The apparatus provides braking by releasably contacting at least one of each of the rollers with at least one of each of the torsional springs so as to deflect and then release the torsional spring as the sprocket assembly rotates about the hub assembly. The braking apparatus accomplishes a consistent braking torque essentially independent of friction by first loading a torsional spring, then decoupling the loaded spring from the braking torque. The decoupled spring is then allowed to dissipate its stored energy by self-damped oscillation at a rate that does not affect the braking torque.
A specific degree of braking is provided by employing the adjustment means to adjust the separation distance between the sprocket assembly and the hub assembly, and thus the separation distance between the rollers and the torsional springs, thereby adjusting the amount of engagement between the rollers and the torsional springs, and thus the amount of spring loading.
The present invention, therefore, is advantageously suitable for use in any service in which a compact, lightweight, mechanically reliable, smoothly-operating, and adjustable braking apparatus is required.